echo displays flashes, screen usage and before and after display time.

Some of the main elements of our study today

Format of the standard command

Command  (COMMAND) [ options ] ... [ parameters (ARGUMENTS ...)]

options : Enable or disable some or some of the features of a command

parameters : command-Action object , such as file name , user name, etc.

First, let's take a look at some of the basics of Linux learning commands

who queries the current user

Hostname Display host name

Lsb_release–a Display System version

LSB (Linux stardard base): Linux standard library

Gedit Graphics tools can only be used for graphical interfaces

Nano Low-level text editing tools

(ctrl+o: Write file ctrl+r: Read file ctrl+w: search character )

Cat View text file

/etc/issue

/etc/centos-release These three files are the system version number file

Ctrl+d Refresh Login Interface

PWD View current folder

Type Displays the specified command types

Ifconfig View IP

uname Viewing the kernel version

Free View Memory

Hash can display external commands that have been loaded into memory

DF View hard disk partition

Id–u Viewing user IDs

CP Copy File command

RM Delete File command

MV move File command

TTY view current terminal equipment

Which viewing the path of an external command

Whereis Viewing the path to a file

Unalias Canceling aliases

Touch generates an empty file

Logout Logoff

\, execute the file under directory , " these can not use aliases

Enable-n Disabling internal commands

Date display and modify software time

Clock display and modify hardware time

Cal Calendar

And some of the differences and uses of the CentOS system

graphical interface : Ctrl+shift+n Add a terminal

Ctrl+shift+t Add a label

Ctrl+shift+w Delete a label

ctrl+shift++ put large characters

Ctrl+alt+f1-6 is a character , F7 is a graphic ---centos5

Ctrl+alt+f1 is a graphic , f2-6 is a character ---centos6,7

CHVT (change virtual ternmal) switch Terminal

CHVT can only be used for local switching

CentOS 6 Normal user cannot switch terminal in graphics slice

CentOS 7 Normal users cannot switch terminals under the graphical interface

StartX Open the graphical interface (not open the mode , but open the graphics application , init 5 is switch mode )

the difference between CentOS 6.8 and CentOS 7.2

the Poweroff of CentOS 6.8 and CentOS 7.2 are powered off .

and the CentOS 7.2 Halt is constantly powered off

and learned some specific uses of ECHO.

echo Hello >/dev/pts/1 send a message to a different terminal

Some of the differences between Linux graphical interfaces

Linux 's graphical interface is based on the X- protocol Protocol

the difference between KDE and GNOME

is different from the underlying development library .

KDE is based on C + + graphics library Development, and GNOME is based on the development of the graphics library .

physical terminals correspond to file /dev/console, which is typically used in single-user mode

virtual terminal corresponding file /dev/pts

How to install and use screen

[[email protected] ~]# DF

Filesystem 1k-blocks used Available use% mounted on

/dev/sda2 103081248 4750432 93087936 5%/

TMPFS 502068 556 501512 1%/DEV/SHM

/DEV/SDA1 194241 34185 149816 19%/boot

/dev/sda3 20511356 333816 19128964 2%/testdir

/dev/sr0 3824484 3824484 0 100%/media/centos_6.8_final

[Email protected] ~]# ram-l/MEDIA/CENTOS_6.8_FINAL/PACKAGES/SC

scap-security-guide-0.1.28-2.el6.noarch.rpm

scap-workbench-1.1.1-1.el6.x86_64.rpm

scenery-backgrounds-6.0.0-1.el6.noarch.rpm

scipy-0.7.2-8.el6.x86_64.rpm

scl-utils-20120927-27.el6_6.x86_64.rpm

screen-4.0.3-19.el6.x86_64.rpm

scrub-2.2-2.el6.x86_64.rpm

scsi-target-utils-1.0.24-18.el6.x86_64.rpm

[Email protected] ~]# ram-l/media/centos_6.8_final/packages/screen-4.0.3-19.el6.x86_64.rpm

There is a rendering under the usage method

Cat/etc/dir_cllors the color properties of the file defined

Homework:

First, let's take the first step to achieve the echo display flashing down and color function

[Email protected] ~]# echo-e "\033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\033[1;31m\ 052\033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\n \033[1;31m\052\033[4m\033[1;31m\052 \033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\033[1;31m\052\033[4m\n \033[1;31m\052\033[4m\033[1;31m\052\ 033[4m\033[1;31m\052\033[4m\n \033[1;31m\052\033[5m\033[0m "

*******

*****

***

*

You can output underlined and colored.

2. Let's continue to learn about the use of screen

650) this.width=650; "Src=" Http://s2.51cto.com/wyfs02/M01/84/8C/wKioL1eUM5uAXwpjAAQWwiq_gq8497.gif-wh_500x0-wm_3 -wmp_4-s_4246230047.gif "title=" screen usage. gif "alt=" wkiol1eum5uaxwpjaaqwwiq_gq8497.gif-wh_50 "/>

3. Now let's show the calendar's

The month and day of the first 10 days and the date of the following 20 days

The first 10 days of output can be done this way

[Email protected] ~]# date-d "Ten day Ago"

Thu Jul 13:19:50 CST 2016

After 20 days the output can be so

[[Email protected]6 ~]# date-d " -20 day Ago"

Sat 13:22:44 CST 2016

echo displays flashes, screen usage and before and after display time.